Blends of vinylidene chlorofluoride polymers with ethylene/vinylene carbonate copolymers



2,934,514 BLENDS F VDIYLIDENE CHLOROFLUORIDE POLYMERS WITHETHYLENE/VINYLENE CARBONATE CQPOLYNERS [val 0. Salyer and John D.Calfee, Dayton, Ohio, as-

signors to Monsanto Chemical Company, St. Louis, Mo., a corporation ofDelaware No Drawing. Application December 11, 1953 Serial No. 397,792 A9 Claims. (Cl. 260--45.5)

This invention relates to polymers of l-chloro-l-fiuoroethylene, alsoknown as vinylidene chlorofluoride. In one aspect theinvention pertainsto improving the'physical properties of homopolymers or copolymers ofvinylidenechlorofluoride. In other aspects the invention provides blendsof polyvinylidene chlorofluoride with ethylene-vinylene carbonatecopolymer.

Polymers of l-chloro-l-fluoroethylene (vinylidene chlorofluoride) havemany properties which are markedly different from those of polymers ofclosely related compounds such as vinyl fluoride, vinylidene chloride,vinyl chloride, or vinylidene fluoride. Polyvinylidene-chlorofluoride isa soft, rubbery material at ordinary temperatures, e.g., 20 C., exhibitshigh tensile elongation,'is comparatively inert chemically, and isnon-inflammable, however, polyvinylidene chlorofluoride is ofcomparatively low tensile strength. Further, on lowering the temperaturefrom room temperature, it quickly becomes stifi and then with only aslight further lowering of tem perature becomes extremely brittle. Thus,its low temperature properties leave much to be desired, and the rangeof temperature in which the material is stifi? rather than rubbery, butyet not brittle, is very small. It will of course be understood that theextent to which any particular polymer of vinylidene chlorofluoride hasone or more of the foregoing characteristics will be dependent to aconsiderable extent upon the method of preparing the polymer, and uponthe presence or absence of other ethylenically unsaturated monomerscopolymerizable with the vinylidene chlorofluoride during thepolymerization procedure. However, the preceding description can betaken as generally applicable to polymers of vinylidene chlorofluoridewith variations as indicated.

The polymerization of vinylidene chlorofluoride is taught in U.S. PatentNo. 2,362,094 to Mary Renoll. Further, copolymers of vinylidenechlorofluoride with other ethylenically unsaturated monomerscopolymerizable'therewith are taught in U.S. Patent No. 2,328,510

to Charles A. Thomas. The present invention is applicable tohomopolymers or copolymers of vinylidene chlorofluoride prepared asgenerally described in said patents, and also to specific variations ofthe processes described therein. The invention is likewise applicable tohomopolymers of vinylidene chlorofluoride prepared by polymerization ofthe monomer at high pressures of at least 5,000 pounds per square inchand preferably at least 15,000 pounds per square inch as described andclaimed in copending application of John D. Calfee, Serial No. 322,157,filed November 23, 1952, now U.S. Patent 2,777,: 835, issued January 15,1957.

v An object of this invention is to provide blends o polymers-ofvinylidene chlorofiuoride having properties improved over said polymersalone. Another object is to improve the low temperature properties ofpolyvinylidene chlorofluoride. A further object is to increase thetensile strength of. vinylidene chlorofluoride polymers. Yet anotherobject is to lower the brittle temperature of vinylidene: chlorofluoridepolymers. A still further object iis to increase the range oftemperature in which yinylidene chlorofluoride polymers are stiff andnon- 2,934,514 Patented Apr 26, 1960 rubbery and yet not brittle. Anadditional object of the invention is to provide blends of vinylidenechlorofluoride polymers with other polymeric materials wherein thecomponents of the blend exhibit high compatibility. Further objects andadvantages will be apparent, to those skilled in the art, from theaccompanying disclosure and discussion;

, bonate copolymer.

In accordance with the present invention in preferred embodiments, oneor more of the foregoing objects are attained by blending withhomopolymers or copolymers of vinylidene chlorofluoride anethylene/vinylene car- Copolymers of ethylene with vinylene carbonateare new materials, and are described in detail in the copendingapplication of Earl W. Glue senkamp and John D. Calfee, Serial No.355,859 filed May 18, 1953, now U.S. Patent No. 2,847,398, issued Aug.12, 1958, the contents of which application are incorporated herein byreference. Preferred blends are those made from rubbery homopolymers orcopolymers of polyvinylidene chlorofluoride, i.e., those that arerubbery at room temperature. Such blends preferably oontain'an amount ofethylene/vinylene carbonate copolymer that is from 1 to 30 weightpercent of the conibined weights of the ethylene/vinylene.carbonatecopolymer and the polymer of vinylidene chlorofluoride In general,vinylidene chlorofluoride polymers are improved in the practice of theinvention, in that the tensile strength isincreased, the tensileelongation is decreased, the temperature at which the material becomesbrittle becomes lower, and/orthe temperature at which the materialchanges from stifi to rubbery character is increased. The preferredblends of this invention are completely compatible at least to theextent that visual observation indicates no lack of clarity ortransparency, and are apparently perfectly homogeneous.

As indicated hereinbefore the invention is of general applicability topolymers of vinylidene chlorofluoride. It is particularly useful forrubbery polymers of vinylidene chlorofluoride that are eitherhomopolymers or that contain a sufiiciently small quantity of comonomer,for example, styrene, acrylonitrile, vinyl chloride, vinyl acetate,vinylidene chloride, methyl methacrylate, vinylfluoride, ethylene, aswill not change the inherently rubbery characteristics of the polymer. IThe terms polyvinylidene chlorofluoride, vinylidene chlorofluoridepolymer, and polymer of vinylidene chlorofluoride). as'used herein areintended to include homo polymers of vinylidene chlorofluoride, i.e.,polymers prepared by subjecting to polymerization a monomeric materialconsisting of vinylidene chlorofluoride as the sole polymerizableconstituent, andcopolymers of vinylidene chlorofluoride with otherethylenically unsaturated monomers copolymerizable therewith. While theinvention can be applied to copolymers of vinylidene chlorofluoridecontaining amajor proportion, i.e., over 50 weight percent, vinylidenechlorofluoride, it is most useful as applied to polymers of vinylidenechlorofluoride prepared from monomers containing from 100 to 85 weightpercent vinylidene' chlorofluoride and 0 to 15' Weight percent of acomonomer. Of course, polymers made from vinylidene chlorofluoride andtwo or more comonomers are also applicable. In any event, the polymeremployed should have a high molecular weight suitable for the useintended. a The term blend is' used herein in a broad sense to includeboth mechanical blends of preformed vinylidene chlorofluoride polymerswith preformed ethylene/vinylene mer can be brought together intointimate admixture by any suitable mechanical means, such as by millingon cold or heated mill rolls, mixing in a Banbury mixer, solution in acommonlsolvent, such as xylene, benzene, pyridine, etc., or mixingemulsions, suspensions, or dispersions of the two polymers andcoagulating same. On the other hand, an ethylene/vinylene carbonatecopolymer can be incorporated in monomeric vinylidene chlorofluoride andthe resulting material subjected to polymerization. For best resultssuch polymerization should be carried to a high conversion, such asgreater than 95 percent conversion to high molecular weight vinylidenechlorofluoride polymer. In preparing such a polymerization blend, theethylene/vinylene carbonate copolymer should be thoroughly andintimately dispersed in the monomeric material prior to polymerization.It is believed highly probable that in the practice of the embodimentsof this invention involving polymerization of vinylidene chlorofiuoridein the presence of preformed ethylene/vinylene carbonate copolymers, acertain amount of interpolymerization occurs between vinylidenechlorofluoride and ethylene/vinylene carbonate copolymer molecules, withthe resultant formation of what can be called a graft polymer, althoughit is by no means certain and is even doubtful that all molecules ofethylene/ vinylene carbonate copolymer become united with one or morevinylidene chlorofluoride monomer units. How- Amer. Chem. Soc., 75,1263, March 5, 19 53.

ever, the invention is not to be limited by any theory of particularreaction mechanism.

Homopolymer or copolymer of vinylidene chlorofiuoride, as describedherein, can be made by any of the known vinylidene chlorofiuoridepolymerization techniques from monomeric material comprising vinylidenechlorofluoride, either with or without ethylene/vinylene carbonatecopolymer present. One of the most common of said techniques is masspolymerization wherein the only material present in the reaction mixtureis the monomer or monomers plus any catalyst and any modifier that maybe used to afiect the molecular weight, plus ethylene/vinylene carbonatecopolymer if it is to be incorporated during the polymerization, and noadded solvent or other reaction medium is present. Suitable catalystsare those that promote free radicals, e.g., peroxy and azo catalysts. Byway of example are benzoyl peroxide, diacetyl peroxide,dimethylphenylhydroperoxymethane, a,u'-azobisisobutyronitrile. Solventpolymerization is similar to mass polymerization, except that a solventfor the monomer and/ or polymer is also present during thepolymerization. Use of a solvent results in a lower molecular weightpolymer. The polymerization of vinylidenechlorofiuoride, with or withoutcomonomers, can also be efiected advantageously by suspension oremulsion techniques. Both of these'techniques involve the use of anon-solvent for the monomer and polymer, but in the suspension techniquethe particles of monomer and ultimately of the polymer are comparativelylarge,

flow at elevated temperatures, and is more easily processed on a hotmill, than isthe case of polymers made at autogenous pressures. Anothervery useful vinylidene chlorofluoride polymerization process forpreparing polymers that can be used in the practice of the presentinvention employs penetrating ionizing radiation, prefer ably gamma-raysfrom radioactive materials such as cobalt-60, as in accordance with theinvention described and iclaimed in the copending application of WilliamH. Yanko and John D. Calfee, Serial No. 318,098, filed October 31, 1952.

The materials blended with polymers of vinylidene chlorofiuoride in thepractice of the present invention are copolymers of ethylene withvinylene carbonate. Properties of vinylene carbonate and methods ofpreparing same are described by Newman and Addor, Jour. Vinylenecarbonate has the structural formula:

based upon the combined Weights of the monomers entering into thecopolymer. In its broadest aspects the invention contemplates use ofpolymers of ethylene conwhile in the emulsion procedure the particlesare quite small and the final product is a stable latex. A suitablemethod for effecting the suspension polymerization of vinylidenechlorofluoride is to employ water and a small amount of an addedsuspending agent, such as a vinyl acetate-maleic anhydride copolymer orcertain phosphates, a lauroyl peroxide catalyst, and a limited amount ofan emulsifier such as glyceryl monostearate. A suitable emulsionpolymerization procedure is to "employ water along with potassiumpersulfate catalyst, any suitable emulsifier, and no polymerizationmodifier. Emulsion and suspension polymerization can be effected attemperatures which are chosen in accordance with the catalyst systemused but which may for example be from 40 C. to C. Use of a highpressure, i.e., at least 5000 pounds per square inch, is a particularlyadvantageous method of polymerizing vinylidene chlorofluoride, andgenerally resultsin polymer that is tougher, higher in molecular weight,has greater resistance to taining the smallest significant quantity ofvinylene carbonate, which may be 1 weight percent or less, and at theother extreme the use of polymers of vinylene carbonate containing thesmallest significant quantity of ethylene which may be 1 weight percentor less, and all proportions between those extremes. However, ofparticular interest are ethylene/vinylene carbonate copolymerscontaining a major proportion by weight of ethyleneand a minorproportion by weight of vinylene carbonate combined in the copolymen'cmaterial. Copolymer compositions within the range of ethylenezvinylenecarbonate weight proportions of 99:1 to 70:30 are ordinarily most usefulin the practice of the invention. It is often preferred to preparecopolymers by polymerization of monomeric material comprising ethyleneand vinylene carbonate, containing a sufliciently high proportion ofethylene to produce a polyethylene-like material, i.e., a high molecularweight normally solid polymer having the general properties ofpolyethylene per se, i.e., polyethylene prepared from monomeric materialconsisting of ethylene.

Anysuitable combination of polymerization conditions resulting in theformation ofa copolymer from a monomeric material comprising ethyleneand vinylene carbonate can be employed. However, in preferredembodiments a monomeric material comprising ethylene and vinylenecarbonate is subjected to copolymerization at highpressures, preferablyat least 5000 pounds per square inch. Pressures of at least 15,000pounds per square inch are more preferably employed, resulting in aprodnot having high self-compatibility (homogeneity). Often optimumresults are obtained at pressures within the range of 20,000 to 40,000pounds per square inch. There is no particular upper pressure limitexcept that imposed by equipment'limitations and pressures up to 200,000pounds per square inch and even higher are suitable. It will beunderstood that suitable precautions should be observed in effectingthis" polymerization process; includ ing the use of rupture discs,barriers, and other well-known means for carrying out high pressurereactions withsafety. It is possible to have a combination of reactionconditions resulting in an explosive reaction, and this should beguarded against by known means. However, technical facilities for thecommercial use of high pressures have been adequately developed, andtherefore the high pressures employed are no barriers to commercial useof the high pressure copolymerization process. The copolymerization ispreferably carried out at temperatures within a fairly broad range,which is preferably 35 C. to 125 C. The preferred range is 50 C. to 100C.

The invention in its broadest aspects is not departed from byblendingvinylidene chlorofluoride polymers with ethylene/vinylenecarbonatecopolymers made by providing, in addition to ethylene andvinylene carbonate, other monomeric materials capable of entering intothe polymerization reaction. Thus, vinyl chloride, vinylidenechlorofluoride, vinyl acetate, vinyl fluoride, propylene, styrene,acrylonitrile, and other unsaturated organic compounds can be used ascomonomers along with the ethylene and vinylene carbonate. This ofcourse will afiect the polymer properties but the amount can be chosenso as to retain the advantageous results of the copolymerization ofvinylene carbonate with ethylene.

' Incopolymerizing ethylene with vinylene carbonate it is preferred toemploy catalysts of the free-radical promoting type, principal amongwhich are peroxide-type polymerization catalyst and azo-typepolymerization c'atalysts, e.g,, diacetyl peroxide,dirnethylphenylhydroperoxymethane, diazoaminobenzene, in small butcatalytic amounts usually within the range of 0.001 to 0.5 percentbyweight of the comonomers. The ethylene/vinylene carbonatecopolymerization can be effected in the pres- .enceof catalytic amountsof oxygen, as within the range of to 200 parts oxygen per million partsmonomeric material on the weight basis. The copolymerization can also beeffected under the influence of ionizing radiation of polymerizingintensity, such as gamma rays provided by cobalt-:60 or otherradioactive substances, using the general procedures described andclaimed in the copendingapplication of William H. Yanko and John D.Calfee, SerialNo. 318,098, filed October 31, 1952. Copolymers ofethylene and vinylene carbonate employed in accordance with the presentinvention are inclusive of modified polymeric materials known astelomers, obtained by carrying out the copolymerization in the presenceof materials which are non-polymerizable under the conditions employedbut whichcombine with a plurality of units of the monomers, e.g., carbontetrachloride, organic acids, esters, mercaptans, alcohols, etc.Additional details directed to the preparation of, ethylene/vinylenecarbonate copolymers, which canbe used in the present invention, will befound in the above-mentioned copending application of Earl W.Gluesenkamp and John D. Calfee, Serial No. 355,859, filed May 18, 1953.

vinylene carbonate units in the ethylene/vinylene carbonate' copolymersare subject to hydrolysis, whereby part or. all of said units areconverted to units of the folowing type in the polymer:

H H 0 0-, 0 o H ,H

The present invention includes blends of vinylidene chlorofluoridepolymers with ethylene/vinylene carbonate copolymers that have undergonehydrolysis, and even that subsequent to hydrolysis have been subjectedto further treatment to react other materials with part or all of thehydroxy groups, e.g., with aldehydes to produce acetals.

Particularly useful compositions of the present invention are blends offrom 99 to 50 parts by weight of vinylidene chlorofluoride polymer withfrom 1 to 50 parts by weight of ethylene/vinylene carbonate copolymer,and

often preferably from 95 to 75 parts vinylidene chlorofluoride polymerwith from 5 to 25 parts ethylene/vinylene carbonate copolymer. Suchblends can also include, if desired, additional materials such asplasticizers, thermal stabilizers, fillers, dyes, pigments, otherpolymers, and the like. Those skilled in the art, having had the benefitof the present disclosure, will be able to choose by simple testssuitable proportions of a particular vinylidene chlorofluoride polymerand a particular ethylene/vinylene carbonate copolymer to give a blendhaving characteristics desired for a particular use.

Blends prepared in accordance with the present invention can be used forpreparation of flexible films, tubing or moldings. If desired the blendcan be modified by plasticization for additional softening, filled withreinforcing agents, colored by addition of suitable colorants,

and/or vulcanized by the incorporation of appropriate accelerators andcross-linking agents. End use articles which might be fabricated fromthe blend, include: Flexible films used as shower curtains, foodpackaging, or in other applications where freedom from plasticizerextraction and exudation problems would be advantageous. Medical andsurgical tubing use is also possible, for the same reason. Asvulcanizates in rubber applications the blends have the advantages ofgood initial color and excellent resistance to ozone and otherdegradative influences.

The following examples provide details of certain preferred embodimentsof the invention. The data are to be taken as exemplary, and theinvention in its broadest aspects is not limited to the particularconditions, proportions, and materials set forth therein.

Example 1 Polyvinylidene chlorofluoride employed in Example 3 below wasprepared in the following manner. Highlypurified vinylidenechlorofluoride monomer was polymerized at 35,000 pounds per square inchpressure in the presence of gamma-radiation from a 50-millicurie cobalt-60 source. After 64 hours at 50 C. under these conditions,polyvinylidene chlorofluoride of high molecular weight was formed in 74percent yield. Properties of this polymer are given in Example 3 below.

Example 2 The ethylene-vinylene carbonate copolymer employed in Example3 below was prepared as follows:

A mixture of ethylene and vinylene carbonate monomers (5 to 1 weightratio) was polymerized at 20,000 pounds per square inch witha,a-azodiisobutyronitrile catalyst. The bomb was charged with themonomer mixture at 78 C. and while the mixture was still cold,

it was pressured to 6000 pounds per square inch with Water. As thetemperature rose to about C., the pressure reached a maximum of 22,000pounds per square inch. Under these conditions rapid polymerizationoccurred (1.75 hours) and the pressure dropped to 12,000 pounds persquare inch. The copolymer was formed in 25 percent yield. It was foundby direct oxygen analysis to contain 10.7 weight percent vinylenecarbonate units in the copolymer.

The ethylene-vinylene carbonate copolymer had the following properties:

Tensile strength at failure, p.s.i 2229. Tensile elongation at failure,percent 470. Clash-Berg data:

Clash-Berg modulus characteristics:

A. Brittle tempemature (T C.

. 8 patible,as indicated by the visual observation that the blend wasclear, transparent and homogeneous.

While the invention has been ,described with particular reference tovarious preferred embodiments thereof, it

for most uses by virtue of the large increase in the tensile strengthand a moderate reduction in the tensile elongation. The components ofthe blend were completely comwill be appreciated that variations fromthe details given Rubber temperature herein can be effected withoutdeparting from the inven- This test is a measure of the stiffness of aplastic speciti n i its bro dest aspects.

men as a function of temperature, measured by means of W cl im; atorsional test. The test is essentially that described by s 1, A bl d fa vinylidene hlorofluoride polymer with Clash and Berg, Industrial andEngineering Chemistry, an tb l i l carbonate copolymen 1218 The brittletemperature 1) is the 2. Ablend of a'vinylidene chlorofluoridehornopolymer temperature at which the stiffness modulus is 135,000 ith nthyleneevinylene carbonate copolymer. P- The rubber temperature 2000) isthe temperature 3. A blend of a vinylidene chlorofluoride polymer withat Which the StiiTHeSS modulus is 2 a normally solid polyethylene-likeethylene-vinylene car- Tensile properties: bonate copolymer containing amajor proportion by S Hen gth to break p Si weight of ethylene and aminor proportion by, weight of Elongation to teem vinylene carbonate 1nsaid copolymer.

4. An intimate admixture of from 99 to 70 parts by These tests aredetermined by the standard tests ASTM weight of a vinylidenechlorofluoride polymer with from D638-52T and D412-41. 1 1 to 30 partsby weight of an ethylene-vinylene carbonate Exam, 1 3 copolymercontaining from 1 to 30 weight percent vinylene carbonate in saidcopolymer.

Ninety parts y weight-0f polyvinylidene chlorofluoride 5. An intimatemechanical admixture of preformed P p as described in Example 1, and 10Parts by polyvinylidene chlorofluoride with a lesser quantity by weightof ethylene/vinylene carbonate copolymer prepared weight f a r f r dethylenewinylene carbonate as described in Example 2, were intimatelyblended by polymer comprising a major proportion b Weight f mixing thecomponents for five minutes or. longer on h l d a minor proportion b iht f i 1en 3" X 8" rubber IOllS, steam heated to flbOlJt 150 0-,carbonate in said copolymer. rotating at 18 and 24 rpm. respectively,and having a 6, A polymer bl d t i i f 95 t 85 parts by nip clearance of0.020 orless. During the blending opweight of polyvinylidenechlorofluoride and from 5 to 15 er the hatch Was mixed frequently yStripping from parts by Weight of a normally solid polyethylene-like therolls and turning using a'doctor blade or knife. When ethylene-vinylenecarbonate copolymer comprising from the batch had been thoroughlyhomogenized, it was sheeted 70 to 99 i h percent h l n nd f 30 t 1weight ofi the rolls, cooled, and cut into strips or granulated for 1percent vinylene Carbonate i id copolymer, molding and testing. 7. Ablend according to claim 1 wherein said vinyli- TeStS 0f P y PIOPeItieSWere made 011 the blend dene chlorofluoride polymer is a copolymer ofvinylidene and also on the polyvinylidene chlorofluoride containing chlooflu id i h up to 15 i h percent f an h l 110 ethylene/vinyleneCarbonate p y The tests cally unsaturated monomer copolymerizabletherewith. were made on test specimens compression molded at 8, A bl daccording t l i 1 ad b m hani ally COnditiOhS 0f Preeessing, moldingtesting r mixing preformed vinylidene chlorofluoride polymer andidentical and direct comparisons were obtained between preformedethylene-vinylene bo at 'co olymer, the polyvinylidene chlorofluorideand the same material 9, A blend according to claim l-made bypolymerizing containing the ethylene/vinylene carbonatecopolymervinylidene chlorofluoride containing preformed ethylene- Dataare as follows: vinylene carbonate copolymer.

Tensile Properties at Clash-Berg Data Break Composition Appear-Strength, Elongation, T1, 0. r 0. Stifiiex p.s.i. Percent range, 0.

Polyvinylidene chlorofluoride 1,083 1, 0 10 10 Clear. Polyvinylidenechlorofluoride ethylene/ 1, 475 1, 100 -3. 7 13. 9 17, 6 Cl ar,

vinylene carbonate copolymer blend.

It will be seen that incorporation of the ethylene/vinylene carbonatecopolymer into the polyvinylidene chlorofluoride significantly reducedthe brittle temperature (T References file of thls patent andsignificantly raised the so-called rubber temperature UNITED STATESPATENTS (T These effects resulted in almost doubling the a tr n itiotemperature range (Stifiiex range). Further, 0 2,542,771 Hanford et a1 21951 he polyvinylidene chlorofluoride was made more suitable 2,563,771Adelson 1951 OTHER REFERENCES Heyes: 637 O.G. 591, August 8, 1950.

1. A BLEND OF A VINYLIDENE CHLOROFLUORIDE POLYMER WITH ANETHYLENE-VINYLENE CARBONATE COPOLYMER.